In a clinical positron emission tomography (hereinafter referred to as PET) device, there are as many as thirty thousand pieces of detectors. Thirty thousand electronic processing channels are required to directly read electrical signals generated by every detector. And a large number of electronic channels will make the whole PET electronic system expensive and hard to realize.
For this case, researchers focus on the research and development of channel multiplexing technology for reading a detector signal. At present, the mainstream reading channel multiplexing method is: reading detector signals by arranging the detector signals in rows and columns and reading output signals after being weighted by a resistor network.
Multiplexing by using the resistor network can effectively decrease reading channels of a detector and solve the problem of overmuch channels. However, when applying the resistor network, equivalent resistances of the resistor network for different detectors are different due to the difference of signal access points, thus finally resulting in a big difference in output signal amplitudes of different detectors and a requirement of a higher dynamic range of a subsequent reading circuit. And the existing normal processing circuit has a finite dynamic range, the signal-to-noise ratio is poor when inputting a small signal, while the problem of saturation also appears when inputting an overlarge signal. So on account of the above technical problems, it is necessary to provide an improved channel multiplexing method for reading a detector signal to overcome the foregoing defects and effectively solve the problem of an overlarge dynamic range of output signals after multiplexing channels for detectors.